package demo04;

public class A {

    public static void main(String[] args) {
        Data data = new Data();

        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();

        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();


        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "C").start();

        new Thread(()->{
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "D").start();
    }
}

// 等待 --> 业务 --> 通知
class Data {
    private int number = 0 ;

    public synchronized void increment() throws InterruptedException {
        if (number != 0) {
            // 等待
            this.wait();
        }
        number++;
        System.out.println(Thread.currentThread().getName() + " => " + number);
        // 通知其他线程
        this.notify();
    }

    public synchronized void decrement() throws InterruptedException {
        if (number == 0) {
            // 等待
            this.wait();
        }
        number--;
        System.out.println(Thread.currentThread().getName() + " => " + number);
        // 通知其他线程
        this.notify();
    }
}
